These individual tarts make a great starter or light lunch served warm with a salad.
Make the pastry. Put the butter and flour in a food processor and blitz to fine breadcrumbs. Add the egg yolk and 1 tsp of water and pulse until the mixture forms a dough. Tip out the dough onto a lightly floured surface, shape into a ball, wrap in cling film and chill it while you make the filling.
For the filling, heat the olive oil in a large frying pan over a medium heat. Add the peppers and courgettes and fry until softened but not browned. Transfer to a bowl and leave to cool.
Heat the oven to 200°C/180°C fan/400°F/Gas 6. Lightly flour your work surface and roll out the chilled dough until 3mm thick. Cut out 12 circles each 16cm in diameter, re-rolling the trimmings as necessary. Use the circles to line your tart tins, trimming the edges to neaten. Chill the pastry cases for 10 minutes.
Line the chilled cases with your greaseproof squares and fill with rice or baking beans, then transfer to a baking tray and bake the cases blind for 10 minutes. Remove the paper and rice or beans, and return the cases to the oven for a further 5 minutes, until golden and crisp. Reduce the oven to 160°C/140°C fan/315°F/Gas 2–3.
Divide the pepper and courgette mixture equally between the pastry cases. Add the diced beetroot. In a separate bowl mix together the eggs, milk and thyme leaves and season with salt and pepper. Pour equal amounts of the mixture over the vegetables.
Crumble the goat’s cheese over, top with a sprinkling of pine nuts and bake for 12–14 minutes, until the cheese is golden, the pine nuts have taken on a little colour and the filling is hot. Remove from the oven and serve warm.